CONTROL SYSTEM FOR DEEP SET SUBSURFACE VALVES

摘要

The hydraulic control system for operating a flow tube in a subsurface safet y valve is disclosed. An isolation piston is used in conjunction with an operating control line and an engagement control line. Both control lines run from the surface. The isolation piston is spring loaded to equalize pressure across a dynamic piston to allow the flow tube t o be shifted by a power spring to allow in turn the subsurface safety valve to close. Application of pressure on the engagement control line directs pressure applied through the operating contr ol line to the top of the dynamic piston thus shifting the flow tube downwardly to open the subsurface safety valve. In an alternative embodiment, a coaxial control line directs fluid to the to p of the dynamic piston and additionally to a parallel path leading to the bottom of the dynamic piston where a control valve is mounted. The control valve can be actuated hydraulically, electronically or other ways such that when it is closed the pressure applied to the dynamic piston shift s the flow to open the subsurface safety valve. A loss of signal to the control valve equalizes the dynamic piston allowing the flow tube to shift.